#include <netinet/in.h>
#include <alloca.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#define TIMEOUT_SECS 60
#define BUFFER_SIZE 4096

#include "ftp.h"

static int ftpCheckResponse(int sock, char ** str);
static int ftpCommand(int sock, char * command, ...);
static int ftpReadData(int sock, int out);
static int getHostAddress(const char * host, struct in_addr * address);

static int ftpCheckResponse(int sock, char ** str) {
    static char buf[BUFFER_SIZE + 1];
    int bufLength = 0; 
    fd_set emptySet, readSet;
    char * chptr, * start;
    struct timeval timeout;
    int bytesRead, rc;
    int doesContinue = 1;
    
    while (doesContinue) {
	FD_ZERO(&emptySet);
	FD_ZERO(&readSet);
	FD_SET(sock, &readSet);

	timeout.tv_sec = TIMEOUT_SECS;
	timeout.tv_usec = 0;
    
	rc = select(sock + 1, &readSet, &emptySet, &emptySet, &timeout);
	if (rc < 1) {
	    if (rc==0) 
		return FTPERR_BAD_SERVER_RESPONSE;
	    else
		return FTPERR_UNKNOWN;
	}

	/* We got a response - make sure none of the response codes are in the
	   400's or 500's. That would indicate a problem */

	bytesRead = read(sock, buf + bufLength, sizeof(buf) - bufLength);

	bufLength += bytesRead;

	buf[bufLength] = '\0';

	start = chptr = buf;
	if (start[3] == '-') 
	    doesContinue = 1;
	else {
	    doesContinue = 0;
	    if (str) *str = start + 4;
	}

	if (*start == '4' || *start == '5') {
	    return FTPERR_BAD_SERVER_RESPONSE;
	}
	while (chptr < (bufLength + buf)) {
	    if (*chptr == '\n') {
		start = chptr + 1;
		if ((start - buf) < bufLength) {
		    if (start[3] == '-') 
			doesContinue = 1;
		    else
			doesContinue = 0;
		    if (*start == '4' || *start == '5') {
		        return FTPERR_BAD_SERVER_RESPONSE;
		    }
		}
	    }
	    chptr++;
	}

	if (*(chptr - 1) != '\n') {
	    memcpy(buf, start, chptr - start);
	    bufLength = chptr - start;
	} else {
	    bufLength = 0;
	}
    }

    return 0;
}

int ftpCommand(int sock, char * command, ...) {
    va_list ap;
    int len;
    char * s;
    char * buf;
    int rc;

    va_start(ap, command);
    len = strlen(command) + 1;
    s = va_arg(ap, char *);
    while (s) {
	len += strlen(s) + 1;
	s = va_arg(ap, char *);
    }
    va_end(ap);

    buf = alloca(len + 1);

    va_start(ap, command);
    strcpy(buf, command);
    strcat(buf, " ");
    s = va_arg(ap, char *);
    while (s) {
	strcat(buf, s);
	strcat(buf, " ");
	s = va_arg(ap, char *);
    }
    va_end(ap);

    buf[len - 1] = '\n';
    buf[len] = '\0';
     
    if (write(sock, buf, len) != len) {
        return FTPERR_SERVER_IO_ERROR;
    }

    if ((rc = ftpCheckResponse(sock, NULL)))
	return rc;

    return 0;
}

static int getHostAddress(const char * host, struct in_addr * address) {
    struct hostent * hostinfo;

    if (isdigit(host[0])) {
      if (!inet_aton(host, address)) {
	  return FTPERR_BAD_HOST_ADDR;
      }
    } else {
      hostinfo = gethostbyname(host);
      if (!hostinfo) {
	  errno = h_errno;
	  return FTPERR_BAD_HOSTNAME;
      }
      
      memcpy(address, hostinfo->h_addr_list[0], hostinfo->h_length);
    }
    
    return 0;
}

int ftpOpen(char * host, char * name, char * password, char * proxy) {
    static int sock;
    /*static char * lastHost = NULL;*/
    struct in_addr serverAddress;
    struct sockaddr_in destPort;
    struct passwd * pw;
    char * buf;
    int rc;

    if (!name)
	name = "anonymous";

    if (!password) {
	pw = getpwuid(getuid());
	password = alloca(strlen(pw->pw_name) + 2);
	strcpy(password, pw->pw_name);
	strcat(password, "@");
    }

    if (proxy) {
	buf = alloca(strlen(name) + strlen(host) + 5);
	sprintf(buf, "%s@%s", name, host);
	name = buf;
	host = proxy;
    }

    if ((rc = getHostAddress(host, &serverAddress))) return rc;

    sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
    if (sock < 0) {
        return FTPERR_FAILED_CONNECT;
    }

    destPort.sin_family = AF_INET;
    destPort.sin_port = htons(IPPORT_FTP);
    destPort.sin_addr = serverAddress;

    if (connect(sock, (struct sockaddr *) &destPort, sizeof(destPort))) {
	close(sock);
        return FTPERR_FAILED_CONNECT;
    }

    /* ftpCheckResponse() assumes the socket is nonblocking */
    if (fcntl(sock, F_SETFL, O_NONBLOCK)) {
	close(sock);
        return FTPERR_FAILED_CONNECT;
    }

    if ((rc = ftpCheckResponse(sock, NULL))) {
        return rc;     
    }

    if ((rc = ftpCommand(sock, "USER", name, NULL))) {
	close(sock);
	return rc;
    }

    if ((rc = ftpCommand(sock, "PASS", password, NULL))) {
	close(sock);
	return rc;
    }

    if ((rc = ftpCommand(sock, "TYPE", "I", NULL))) {
	close(sock);
	return rc;
    }

    return sock;
}

int ftpReadData(int sock, int out) {
    char buf[BUFFER_SIZE];
    fd_set emptySet, readSet;
    struct timeval timeout;
    int bytesRead, rc;
    
    while (1) {
	FD_ZERO(&emptySet);
	FD_ZERO(&readSet);
	FD_SET(sock, &readSet);

	timeout.tv_sec = TIMEOUT_SECS;
	timeout.tv_usec = 0;
    
	rc = select(sock + 1, &readSet, &emptySet, &emptySet, &timeout);
	if (rc == 0) {
	    close(sock);
	    return FTPERR_SERVER_TIMEOUT;
	} else if (rc < 0) {
	    close(sock);
	    return FTPERR_UNKNOWN;
	}

	bytesRead = read(sock, buf, sizeof(buf));
	if (bytesRead == 0) {
	    close(sock);
	    return 0;
	}

	if (write(out, buf, bytesRead) != bytesRead) {
	    close(sock);
	    return FTPERR_FILE_IO_ERROR;
	}
    }
}

int ftpGetFile(int sock, char * remotename, int dest) {
    int dataSocket;
    struct sockaddr_in dataAddress;
    int i;
    char * passReply;
    char * chptr;
    char * retrCommand;
    int rc;

    if (write(sock, "PASV\n", 5) != 5) {
        return FTPERR_SERVER_IO_ERROR;
    }
    if ((rc = ftpCheckResponse(sock, &passReply)))
	return FTPERR_PASSIVE_ERROR;

    chptr = passReply;
    while (*chptr && *chptr != '(') chptr++;
    if (*chptr != '(') return FTPERR_PASSIVE_ERROR; 
    chptr++;
    passReply = chptr;
    while (*chptr && *chptr != ')') chptr++;
    if (*chptr != ')') return FTPERR_PASSIVE_ERROR;
    *chptr-- = '\0';

    while (*chptr && *chptr != ',') chptr--;
    if (*chptr != ',') return FTPERR_PASSIVE_ERROR;
    chptr--;
    while (*chptr && *chptr != ',') chptr--;
    if (*chptr != ',') return FTPERR_PASSIVE_ERROR;
    *chptr++ = '\0';
    
    /* now passReply points to the IP portion, and chptr points to the
       port number portion */

    dataAddress.sin_family = AF_INET;
    if (sscanf(chptr, "%d,%d", (int *) &dataAddress.sin_port, &i) != 2) {
	return FTPERR_PASSIVE_ERROR;
    }
    dataAddress.sin_port = htons((dataAddress.sin_port << 8) + i);

    chptr = passReply;
    while (*chptr++) {
	if (*chptr == ',') *chptr = '.';
    }

    if (!inet_aton(passReply, &dataAddress.sin_addr)) 
	return FTPERR_PASSIVE_ERROR;

    dataSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
    if (dataSocket < 0) {
        return FTPERR_FAILED_CONNECT;
    }

    retrCommand = alloca(strlen(remotename) + 20);
    sprintf(retrCommand, "RETR %s\n", remotename);
    i = strlen(retrCommand);
   
    if (write(sock, retrCommand, i) != i) {
        return FTPERR_SERVER_IO_ERROR;
    }

    if (connect(dataSocket, (struct sockaddr *) &dataAddress, 
	        sizeof(dataAddress))) {
	close(dataSocket);
        return FTPERR_FAILED_DATA_CONNECT;
    }

    if (ftpCheckResponse(sock, NULL)) {
	close(dataSocket);
	return FTPERR_BAD_SERVER_RESPONSE;
    }

    rc = ftpReadData(dataSocket, dest);
    close(dataSocket);
    
    if (rc) return rc;

    if (ftpCheckResponse(sock, NULL)) {
	return FTPERR_BAD_SERVER_RESPONSE;
    }

    return 0;
}

void ftpClose(int sock) {
    close(sock);
}

const char *ftpStrerror(int errorNumber) {
  switch (errorNumber) {
    case FTPERR_BAD_SERVER_RESPONSE:
      return ("Bad FTP server response");

    case FTPERR_SERVER_IO_ERROR:
      return("FTP IO error");

    case FTPERR_SERVER_TIMEOUT:
      return("FTP server timeout");

    case FTPERR_BAD_HOST_ADDR:
      return("Unable to lookup FTP server host address");

    case FTPERR_BAD_HOSTNAME:
      return("Unable to lookup FTP server host name");

    case FTPERR_FAILED_CONNECT:
      return("Failed to connect to FTP server");

    case FTPERR_FAILED_DATA_CONNECT:
      return("Failed to establish data connection to FTP server");

    case FTPERR_FILE_IO_ERROR:
      return("IO error to local file");

    case FTPERR_PASSIVE_ERROR:
      return("Error setting remote server to passive mode");

    case FTPERR_UNKNOWN:
    default:
      return("FTP Unknown or unexpected error");
  }
}